Wednesday, April 6, 2011

Cups - job cancellation - group membership is the key

There are several printing systems which you might use in Debian, depending on your desktop of choice (Xfce, KDE, Gnome, Lxde, etc)

If you use cups, then one of the tasks you will want, at some point, is "Job cancellation"

When this task is first required, I find myself immediately leaping to the following questions:

What port is the cups 'admin interface' running on so I can open the admin web page in a browser?

...and...

Do I enter admin / root where the authentication prompt asks for "User Name"?

...and...

Where in /etc/ can I find the password for the admin / root user?

...and lastly I am probably about to head out to websearch for 'cups admin default password'

Turns out I am asking all the wrong questions and wasting my time.

How to do Job cancellation in cups:

( should not require a 'sign-in' - the key is group membership )

On a multi-user system, not all users will necessarily have access to a printer.( It could be that your "Industrial Colour Laser 9000" is not something you want every team in the office to be able to access )

If your OS of choice has a 'server distribution' and 'desktop distribution' (Ubuntu perhaps or the Red Hat / Fedora combination), then some might feel it is appropriate for the 'desktop' version to have automatic membership of lpadmin.

Once your username is a member of lpadmin, then you can proceed to this screen:

Which will list the queued jobs and offer you the option to 'Cancel' for each job in the queue*.

( Url is http://localhost:631/jobs/ which you can bookmark in your browser )

*Note: you might have to log out & log back in again, in order for the new group membership to take effect, then afterwards accesshttp://localhost:631/jobs/

GNU / Linux has several options for backend printing systems, as I hinted earlier.

If you prefer a different printing backend, then, for Xfce, the settings here:

...and here ...

...will help you switch to an alternative.

Notes and Further reading:

Cups is not universally liked, and different GNU / Linux distributions use more or less of it to their taste.

Can be accessed from a terminal using a text based web browser (such as links).

Personally I quite like the idea of http://localhost:631/ in a browser for printer control, seems simple and it works. So I do not mind a quick manual group add command, in order to set things up my end :)